1. Field of the Invention
The present invention relates to an electrolytic cell which is especially adapted for the high pressure electrolytic coupling of carbon monoxide to squaric acid, and a system incorporating such cell.
2. Description of Related Art
Processes are known whereby carbon monoxide can be electrolytically coupled to form squaric acid.
U.S. Pat. No. 3,833,489 to Ercoli et al. describes the electrochemical cyclotetramerization of carbon monoxide to produce the squarate ion. Operations using corrodable or non-corrodable anodes are described. Solvents such as amides of phosphoric acid or carboxylic acids, aliphatic ethers, cyclic ethers, liquid polyethers and anhydrous ammonia are taught. Materials such as halides are added to enhance conductivity.
The apparatus described in the above patent is a pressure resistant electrolytic cell in which may be arranged a cylindrical graphite anode and a stainless steel cathode which is also the container. A stirrer is provided and there are introduced into the cell under nitrogen atmosphere auxiliary electrolyte and solvent. The cell is sealed and immersed in a temperature control bath. Carbon monoxide is charged until a certain pressure is attained and direct current is then passed through the solution for the time required for the reaction Upon completion of the reaction, current circulation is stopped, gas is discharged and the suspension in the cathodic zone is removed and subjected to various recovery and work-up procedures.
It will be apparent that the apparatus described above is not suitable for continuous, commercial-type operations.
U.S. Pat. Nos. 4,461,681 and 4,523,980 of James J. Barber are directed to the electrolytic tetramerization of carbon monoxide using anhydrous nitrile solvents and to the separation and recovery of high purity squaric acid from squarate containing solids from the electrolytic reaction. The apparatus described for the electrolytic tetramerization is, illustratively, a Paar bomb equipped with a magnetic stirring vane. An aluminum, titanium or magnesium rod connected via a bulkhead electrical adapter to the positive pole of a power supply is used as anode. After being charged with solvent and auxiliary electrolyte, the bomb was sealed, connected to the negative pole of the power supply, and pressurized with carbon monoxide. Direct current was applied until a certain charge had passed. Gas was vented, and solids were separated as by centrifugation.
It will be apparent that improvements in the apparatus described above are desirable for continuous commercial operations.